Simplified climate modelling. Part 1: The role of CO2 in paleoclimate
Posted on May 29, 2021 by curryja | 49 Comments
by Thomas Anderl
Simple models are formulated to identify the essentials of the natural climate variabilities, concentrating on the readily observable and simplest description. The results will be presented in a series of five articles. This first part shows an attempt to determine the climate role of CO2 from the past. Observations on 400 Mio. years of paleoclimate are found to well constrain the compound universal climate role of CO2, represented by a simple formula.
1. Introduction
Earth presently receives on average 240 W/m2 of insolation (planetary albedo taken into account) [1]. In equilibrium, Earth radiates the same amount back to space, corresponding to -18 °C in the blackbody approximation. The actual surface temperature is far higher with an average of about +15 °C. Therefore, something must be delivering heat to the surface in addition to insolation. When looking for the sources, a hint comes from a well-known experience: clear-sky nights exhibit relatively low Earth surface temperatures while cloudy nights remain relatively warm. Thus, the atmosphere is contributing to the heat variability at the surface, with water molecules as the dominant components.
However during the current geologic eon, the water content in the atmosphere is a passive reactant to otherwise driven temperatures, acting as an amplifier. When looking for the temperature driving processes, key candidates are the insolation (in particular the varying solar activity and modulation by the planetary albedo), tectonic movements (e.g. with their impact on ocean and wind currents), large volcanic activities, forms of life, extra-terrestrial events (bolide impacts, cosmic rays), and atmospheric composition beyond water content. Apparently through history, all these components have played their role in driving Earth’s near-surface atmospheric temperature.
https://judithcurry.com/2021/05/29/simplified-climate-modelling-part-1-the-role-of-co2-in-paleoclimate/
